It is proposed to evaluate the extensibility characteristics of the buccinator musculature in human adult males over both short term and long term. The short-term study will be concerned with influence of a) tooth surface area, b) loading velocity, c) decay factor, d) time between tests, 3) neuro-muscular mediation on elastic quality. The f) within-individual variation and g) between-individual variation will be evaluated. The long-term study will be concerned with the adaptive capabilities of the muscle during a nine month muscle extension period. The instrumentation, via a removable partial in an edentulous space in upper bicuspid-molar region, consists of two servometer miniature metal bellows in series (master bellows outside of mouth) with a pressure transducer-torque motor feedback control. With needle electrodes, E.M.G. simultaneous recordings will be made. Force, displacement, and E.M.G. activity will be recorded, and the application of Caplan's thermodynamic theory (with Hill's equation as a special case) to the resultant muscle data will be made.